Sup Fellas,

Ive been running strong for about 9,000 miles on my
rebuild. L98 #081 305 heads, mild cam and basic bolt
ons.. stock memcal/injectors.

Engine pur is magnificent at start up and at operating
temperature initially, great power throughout and pulls
great. After about a 45mins-hour of cruising.. the motor
seems to be a lot noisier at idle (500-850rpm)

It's not so much a valve train tick, it sounds like
cam, comming from under the throttlebody area-
front of the motor. It's almost like a tappish/tick
that seems to appear only after running the
engine under load for long periods.

Could a worn cam bearing be suspect? It doesnt
make sense why the noise goes away after the
car sits and cools off.. the next day it'll vanish
like I hear nothing! It doesn't add up why it would
come & go with prolonged runs & temperature..

I felt the injectors for excessive chatter and it's not
them. Maybe a lifter or two could be causing the tick.

..haven't reset the lash on the rockers yet, I was going
to last weekend .. I run Crane aluminum Energizer 1.52rr's.
I don't think I could be the rockers though, I would hear
them chatter at variable rpm.

I can't hear anything at WOT, revs clean.. seems
a tad doggy at part throttle though, runs fine uptop
nevertheless =/

Temperature is playing a role in this issue, just seems
like the engine is loose, and Im not sure what to think.

A tad concerned.. I want to pull the intake off
this weekend and take alook around, figure I
might get some opinions on what to think.

Thanks in advance

 

What is the oil pressure doing? does if vary?

 

Consistent, doesn't jump around at all. It gets oil up top
at every rocker, none are dry. She leaks alittle bit back
near the passenger side valve cover. Nothing extreme and
Ive always kept my eye on the levels.

My Y-pipe is awfully close to my oil pan, probably cooks
the oil up pretty nice. But, Ive been running 10w-40 Valvoline
Durablend with no problems.

Car runs and idles nice and cool at 190degress, lubrication
is present. Maybe I can try to pull some timing off of it and
see if it quiets down any..

Other than that, Im not sure what to think

 

As the oil gets hot, it gets thinner, and loose tolerances in bearings start to knock. I've never heard a bad cam bearing, so I can't describe the sound. The first thing that comes to my mind is rod knock, (dull thudding) but that's unlikely if it's a fresh rebuild. An easy way to check the rod bearings is wait until the sound presents itself again, and take off the plug wires one by one and see if it disappears.

 

Ill do that when I get home, Im on the
graveyard shift at the moment.. but, It's
worth a shot.

Seems to me while I was poking around
with a screwdriver to my ear it's comming
from the intake valley, and Im leaning toward
loose rocker, pushrod or collapsing lifter.

I wont dismiss your idea, in fact Ill take it
very serious and see what I can come up
with. Rod knock would mean game over for
me. Ill mothball the car and let it rot in the
garage until my depression passes

 

Well, after further examination.. It's not bottom end (whew)

The noise is definitely drive side of the block, and doesn't
sound horrible. Ill tear the covers off and lash before I get too hasty and do an intake job.

I did however find an exhaust leak contributing to the
noise being heard. Can header leaks become more obnoxious
with temperature? The gasket isnt entirely blown out, but
I could feel some puffing near the primary.

These headers have been through 2 sets of gaskets
within the last 3months, and it's not because Im half
assed.. Probably the gasket set I bought is unqualified
for the task!

Thanks for the paranoia

 

No problem It'd be really great if it's just an exhaust rattle.